Help translate "business French" sentence

Hello Group,

I usually don't have much trouble translating ordinary or literary
French, with the aid of my dictionary, of course, but the following
sentence (from a letter to a friend) seems to be in a business or
commercial form or a type of what we Americans call "legalese". I am
having trouble translating it with any feeling of security. Any help
would be very much appreciated. Here's the sentence:

"Les pensions des régimes salarié et indépendant dont la prise de
cours est antérieure au 1er janvier 1988 sont adaptées au bien-être à
partir de septembre 2007."

Picking the sentence apart, it seems that the subject and verb are:

Les pensions .........sont adaptées. (?? Pensions are adjusted.)
des régimes salarié et indépendant ( I wonder why it isn't "salariés
et indépendants?) My grammar may be failing me here.
la prise de cours (beginning of the course?)
The other phrases seem obvious.

I seem to grasp the general meaning of the sentence, but I would
really appreciate it if an accurate translation can be done.

Many thanks.

Jack